Questions tagged [beam]
Questions about the theory and applications of structural elements designed to resist bending.
179
questions
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51 views
What is the difference between W, S, I, H sections?
W and H sections look pretty much the same. S and I sections have their flanges rounded. What difference does this rounding make, why would an S-section be used instead of W-section for example?
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29 views
How to choose the dimensions for a prestressed I-beam?
I need to design a simply supported symmetric I-beam (for a school problem). However, I can't find much information about the selection of the section or if there exist any standards for that. the ...
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1answer
34 views
steel beam type and size for a clothesline
I have four posts in a square formation. Posts are also square. I want to bolt a beam between two posts on the left and a beam between two posts on the right, and than run some wire between the beams. ...
2
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1answer
51 views
Do the floorboards in timber beam floors have a structural function?
Timber beam floors with perpendicular timber floorboards as indicated in the drawing below are common throughout northern Europe. The floorboards are nailed onto the beams and are quite substantial ...
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1answer
22 views
Centroid of unsymetric bending in T-section
Can anyone please explain how this 24 is coming while calculating the x-cordinate of the centroid.
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2answers
101 views
Maximum induced bending stress within the beam
The Maximum induced bending stress within the beam.
Given that:
$$\frac{My}{I}$$
The beam depth is 300mm, the width is 150mm. The beam is an I section beam with a 5mm wall thickness.
My ...
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1answer
42 views
RHS beam deflection with support on one end
A 1400 mm long galv steel beam, size 40x20x2.
80 mm of the beam on one end is welded in flat position to a platform.
How much weight can I put safely on the other end?
What if instead of being flat ...
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0answers
18 views
Pin connection on beam - FEA analysis
I am establishing a MatLab FEA code for determining the stiffness of a structure. Diagram of the structure is added below.
I have established a code for determining the stiffness of the structure, but ...
0
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2answers
48 views
Boundary conditions for this beam deflection problem
consider the diagram above. I know that deflection is described by the equation
$$EI\frac{d^4y}{dx^4}=p(x)$$
where $L$ is the length of the beam, $E$ is the Young's module, $I$ is the moment of ...
3
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2answers
297 views
Degrees of freedom of an internal hinge in plane beam?
What are the degrees of freedom of an internal hinge in a plane beam?
I understand that the bending moment=0, does this mean there is no slope either?
Or does it have both degrees of freedom of ...
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0answers
26 views
Sign convention for deflection and slope of beam?
What is the sign convention for deflection and slope of a beam as shown in the diagram below?
When I derive the formula using Euler-Bernoulli for deflection and slope myself, I end up with - ...
3
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1answer
53 views
Why is there a row of circular holes in this concrete beam?
The reinforced concrete beam (approximate dimensions 36" x 18") shown in the image below has a row of circular holes at 3/5ths of the height of the cross-section at approximately 300 mm centres.
My ...
2
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1answer
26 views
Shear flow for unequal leg channel
How does the sine part i.e. $\dfrac{\ell\sin(\theta)}{2}$ appear in the calculation of shear flow ($q$)? I mean, if I'm not mistaken, the sine part is the distance from the x-axis to point D, but how ...
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2answers
33 views
Dimensioning of beam pressed by screw in assembly
I need help dimensioning a screw-beam system of a press. I built one prototype but the beam is bending too much.
Below is a sketch of my press. In the middle it has a fixing screw which presses ...
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2answers
48 views
Bending moment in Euler-Bernoulli finite Element
I'm trying to calculate the bending moment distribution on a fixed-fixed Euler-Bernoulli beam. It is known that interelement nodes show different values for the bending moment. What is customary to do ...
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2answers
56 views
What is the strongest way to fasten 8020 extrusions in this arrangement?
I am making a project using 10mm aluminum extrusions. I am trying to connect all three extrusions like the picture below shows and I am going to make my own bracket (in red) out of aluminum since the ...
2
votes
1answer
58 views
Twist “buckling” critical load
I have a very long beam which is subjected to a torque (I have the moments and shear forces with respect to X along the beam). I can calculate the critical load when the beam would bend if it was ...
1
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2answers
43 views
Deflection and stress in a freely rotating beam
How do I calculate the deflection and stress of a beam that is rotating freely (for example in space) when a moment is being applied to it, for example by rocket motors at the ends of the beam?
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1answer
209 views
Problem while solving for the moment of a cantilever beam
As in the first image,
Moment at any point between C and B should be 0.
But when I try to solve it by substituting equal and opposite forces at end C so that anti-clockwise moment of $F(l-a)$ and ...
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0answers
140 views
Problem with cantilever beam and yield strength
Hey, I make a project in which I use a cantilever beam with distributed equal load across the whole beam and I'm using the formulas above to calculate the displacement, moment...
My specifications ...
0
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1answer
62 views
Maximum I-beam girder S12x31.8 span
Does 200lb/in of load on a S12x31.8 over 15 feet seem reasonable? I'm having a tough time trusting the numbers.
Two story house with an attic as below. Dotted lines show load bearing walls W1 and W2. ...
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3answers
194 views
Buckling vs. Yielding Failure of Columns
As I have been working through examples of construction projects, I've noticed that in nearly every case of a structural column (sample size considers only homogeneous material columns, no composite ...
1
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1answer
41 views
What criteria must apply for torsional effects on this beam to be ignored in calcs?
I'm interested in how to work out whether torsional effects can be ignored or not, in calculating the adequacy of a given steel beam in the following idealised eccentric scenario.
Or, equivalently, ...
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1answer
67 views
Modification of Beam Equation for Thin Sheet
I am trying to determine the modulus of elasticity (Young's Modulus) for a rigid paper sheet. The issue I am having is that my results for the Young's Modulus change depending on what orientation (...
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2answers
74 views
Pin joint system displacement question
A pinned system comprising bars of the same material and cross-sectional area is subjected to a vertical load P.
I am required to form a relationship between FAB and P.
The first part of the ...
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0answers
29 views
How to write the equilibrium stress equations for a hollow, rectangular beam?
I have a system consisting of a hollow, rectangular cantilever beam (pictured below). I'd like to write the equilibrium stress equations à la the Cauchy Stress notation.
How do I account for the ...
2
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1answer
62 views
Why are variations zero on the endpoints of a beam?
On Wikipedia derivation on Timoshenko beam equation we arrive at this:
$$ \delta U = \int_L \left[-M_{xx}\frac{\partial (\delta\varphi)}{\partial x} + Q_{x}\left(-\delta\varphi + \frac{\partial (\...
3
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1answer
136 views
How to analyze a bent beam: Stress concentration?
I am analyzing a beam, that has a bend in it. Intuitively and inspecting FEA results using a linear solver, there is a stress concentration at the bend of this I-beam.
The part was not a straight I-...
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1answer
239 views
Calculating area moment of inertia for a beam with underslung plate?
In a number of designs, a beam will have an underslung welded plate attached, as shown below:
In this sketch, a symmetrical standard steel beam/column of dimensions H1 x B1, with web and flange ...
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0answers
54 views
Rotational bending in Timoshenko beam theory
The Wikipedia article on Timoshenko beam theory says:
The model takes into account shear deformation and rotational bending effects,
I am familiar with shear deformation, but what is meant by "...
0
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1answer
93 views
simple supported Beam deflection question involving two point loads and a UDL
so i was given a problem by my mechanical principles teacher to work out the max vertical deflection of a simply supported beam with two point loads one a distance of 5.3 away from A and another 5.9 ...
0
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1answer
392 views
Along which direction is the area moment of inertia taken in bending moment equation?
Is it in the same direction of the applied load or in the co-planar perpendicular direction to the load applied?
0
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1answer
117 views
MSC Nastran - BAR3/4 elements - can't assign any properties
I'm modeling a pipe in Patran, and I'd like to try bar3 and bar4 elements.
I assing the properties CBEAM to my geometry, but when I create the mesh, Patran tell me bar3 and bar4 don't support that ...
2
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3answers
82 views
Do internal / external stresses affect modal frequency?
Imagine a cantilevered beam, fixed on one end and with a tension line connecting the other end to ground (e.g. perpendicular to the length of the beam).
If I increase the tension, does the modal ...
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3answers
150 views
Composite beam- increase in bending moment due to reinforced steel
While trying to solve this question and using the flexure formulas of bending for composite beams I obtained a lower value of moment for steel than for aluminum.How is that possible?
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3answers
101 views
Reaction Forces on a Beam
I'm new to beams and I'm struggling to find the correct vertical reactions forces at support C and E.
The correct answer is 8.58 kN for $V_c$ and -3.58 kN for $V_e$
However, when I ...
0
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2answers
97 views
How to get the bending moment for tie member?
How to get the bending moment for tie member? For the tie member, there is no uniformly distributed load and concentrated load, right? How to get the bending moment? The tension force was found to be ...
3
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3answers
89 views
Why does concentrated shear force on a beam influence the whole beam?
This might be a silly question but can someone explain how this shear force on the right side of the beam causes Qy throught the whole beam?
I understand it mathematically but not conceptually so I ...
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0answers
204 views
Simple beam deflection of cantilever beam
Recently I had need to prove the beam deflection equation for a simple cantilever beam with a point load at the end. The equation would be in reference to the Euler-Bernoulli theory taught in most ...
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2answers
855 views
Simple beam with cantilever ends
I'm trying to find the maximum bending moment and deflection for this symmetrical simple beam. The formulae I can find, deal with either cantilever beams with one fixed end, or continuous beams ...
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2answers
192 views
Statically indeterminate fixed-pinned beam problem
F=32KN; Mf1=60KN-m; Mf2=-58KN-m; g=30KN/m I need to solve this using Force method. Find the reaction at the pinned end.
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2answers
1k views
Stiffness of a cantilever beam
I am working on calculating the stiffness of a cantilever beam by applying a distributed load. I wanted to ask if the distribution of the load on the beam effects its stiffness.
For eg., if I apply a ...
1
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1answer
478 views
Can bending moments for a combination of loads on a simple beam, be calculated by adding the individual B.M. of each load?
This problem is about bending moment of a simple beam subject to a mixture of 4 or 5 UDLs and point loads. The beam is assumed to be rigid enough that deflection of the combined load is "small".
...
2
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2answers
105 views
Indeterminate beam with a guide at each end
I've been battling with a statics question (as attached) and can't for the life of me figure it out.
I've attempted removing the left side guide joint so then there are only 3 reactions and it should ...
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2answers
1k views
Shear force and bending moment for continuous span
It's given that L1 = 5m, L2 and L3= 7.5m, w = 8.9kN/m , I am asked to find the bending moment using these coefficient.. Prior to this , i need to have the value of shear force first.Shear force = ...
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41 views
Possible improved approaches to 6mx3m moment-resisting frame with eccentricity+torsion, in advance of detailed engineer discussion
I'm putting a steel frame in, to "open plan" the rear of a brick cavity-wall terrace house in the UK, which will then have a single storey extension added behind it.
I have already retained a ...
0
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1answer
733 views
Shape Functions of beam element with 3 nodes (quadratic element)
For a two node beam element there are four shape functions for four degree of freedom:
For a straight three node beam element how shape functions are?
Please note that beam is straight and not ...
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1answer
46 views
Big Beam LVL or Glu Lam load capacity to support a gymnast
I need help knowing if I am selecting the correct wood beam.
The load will be all near the center and a 250 pound man will be doing pull ups on it. I would estimate a 1,000 pound dynamic load to be ...
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87 views
What is the optimal shape of a beam subject to three point bending?
Assume we have a beam with density $\rho$ that is subject to three-point bending according to the image above. The beam cross section is rectangular with the variable height $H(x)$ and constant width $...
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1answer
112 views
Calculation of natural frequency in a hinged beam
What I tried: Using the conjugate beam method to find deflection and hence stiffness of the beam, but I am unable to find reactions in the conjugate beam.
